Vertical Profile Optimization for the Clous Civil3d

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AutoCAD Civil 3D 2012

Vertical Profile Optimization on the Cloud

User Manual

January 2012


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Table of Contents

1 Introduction......................................................................................................... 3

2 Installation .......................................................................................................... 4

3 Submitting a Job with a Single EG Centerline .................................................. 63.1 General Parameters ............................................................................................................ 63.2 Borrow/Waste .................................................................................................................... 103.3 Profile Options ................................................................................................................... 11

3.3.1 Maximum Grade ........................................................................................................ 123.3.2 Minimum Grade ......................................................................................................... 123.3.3 Minimum Tangent Length .......................................................................................... 133.3.4 Fix first and last PVI elevation ................................................................................... 13

3.4 Optimization Options ......................................................................................................... 133.4.1 Number of earthwork sections ................................................................................... 143.4.2 Intensity of PVIs ......................................................................................................... 15

3.4.3 Solution precision ...................................................................................................... 153.4.4 Maximum solving time ............................................................................................... 153.4.5 Submission ................................................................................................................ 15

4 Results and Import ........................................................................................... 174.1 PDF Report ........................................................................................................................ 174.2 ASCII Profile ...................................................................................................................... 194.3 LandXML Profile ................................................................................................................ 214.4 Logfile ................................................................................................................................ 22

5 Using Profile Offsets A Case Study .............................................................. 245.1 Preparing the Drawing ....................................................................................................... 245.2 First Submission with Parameter Changes ....................................................................... 25

5.2.1 Design Speed ............................................................................................................ 255.2.2 Surface Profile Selection ........................................................................................... 255.2.3 Maximum Grade ........................................................................................................ 265.2.4 Start and End-PVI elevations .................................................................................... 265.2.5 PVI Intensity ............................................................................................................... 27

5.3 Import and Analysis of Volumes ........................................................................................ 275.4 Change of Excavation Cost ............................................................................................... 29

6 Limitations ........................................................................................................ 316.1 Cross-Sections .................................................................................................................. 316.2 Mass-Haul and Volume Reports ........................................................................................ 31


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3 |Section 1 Introduction

1 Introduction

The geometric design of a road is a crucial part in any highway construction project. Once fixed,the design determines largely the construction costs.

An optimal vertical road profile, with respect to earthwork cost, follows the ground surface asclose as possible. The closer the road is to the ground profile, the fewer earthwork needs to bedone in order to cut or fill sections of the road. However, due to design constraints like slope,grade changes, vertical curve length, etc., it is not always possible to follow the ground surface.Finding the road profile that minimizes the construction costs subject to design constraints is aprocess that we call profile design optimization.

Traditionally, the design of road profiles is done manually by engineers using a mass-diagram. Inthis approach, the vertical profile is evaluated with an integration of the earthwork volumesbetween the road profile and the ground surface. The integral can be plotted by hand or with thehelp of software. After visual inspection of the mass diagram, the engineer changes the profile

and re-computes the volumes. This process is repeated until a satisfying solution is found.

There are several disadvantages using the mass-diagram approach:

The mass diagram does not provide a real costfor a given design. The mass diagram considers uni-directional earthwork only. It does not account

for earthwork that could start on either end of the road. The mass diagram does not account for different costs, such as excavation,

embankment, load, borrow, and waste. The mass diagram cannot combine multiple surface layers in combination with

cut and fills. The mass-diagram approach is a manual approach that is not able to incorporate

design constraints automatically. Due to timely and budgetary constraints, a final alignment is often chosen from a

small selection of possible solutions.

In the cloud-based vertical profile optimization, we address all the above shortcomings of themass diagram with a new Cloud-based algorithm. To access this service, the user needs to usethe Profile Optimization Wizard, which comes as a Civil 3D extension. The installation instructionsfor the extension are given in Section 2.

PVIs are created automatically and the vertical and horizontal position of these PVIs areoptimized with respect to total earthwork cost. The algorithm can handle multiple ground surfacelayers with different earthwork costs, and incorporates borrow and waste pits for differentmaterials.

In our algorithm, only the Existing Ground(EG) centerline is needed for input. However,submission of additional centerline offsets may result in more accurate volume approximationsand, therefore, potentially better solutions. In Section 3 we explain how to use the single EGcenterline approach. Section 5 covers the method of using additional Profile Offsets.

The solution is provided in formats that are ready to be imported into Civli 3D, together with anearthwork planfor the cheapest hauling scheme. Section 4 shows how the solutions are importedand Section 6 shows the limitations of the algorithm.


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4 |Section 2 Installation

2 Installation

1. Launch the Profile Optimizer for Civil 3D 2012 (C3DProfileOpt2012.exe).2. In the installer window, click Next (see Figure 1).

Figure 1: Start installation

3. If you accept the License Agreement, click Next (see Figure 2).

Figure 2: License Agreement


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5 |Section 2 Installation

4. Select AutoCAD Civil 3D 2012 and click on Install (see Figure 3).

Figure 3: Civil 3D version

5. When the install is completed, click Finish (see Figure 4).

Figure 4: Finish install


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6 |Section 3 Submitting a Job with a Single EG Centerline

3 Submitting a Job with a Single EG Centerline

The current algorithm estimates a road width based on the chosen design speed. If a single EGcenterline is used, the cross-sections will be approximated with the assumption that there areretaining walls on either side of the road. Hence, using a single EG centerline only (no offsets)may not produce as accurate results. However, the solving process is significantly faster withoutthe use of offsets. In this section, we discuss the use of a single EG centerline only.

In the single EG centerline mode, we submit an EG profile, and let the optimization service createan entirely new profile. For the following example, we use the file at:http://labs.blogs.com/Silverstar/Silverstar-Tutorial-1.dwg

In order to submit a job, we need to provide at least one EG centerline. Figure 5 shows theSilverstar-Tutorial-1.dwg example with a finished EG centerline.

Figure 5: Silverstar-Tutorial-1.dwg example with EG centerline profile.

3.1 General Parameters

1. Launch the optimization wizard from the AutoCAD Toolbox. Select Autodesk Labs

Technology PreviewsProfile Optimization for AutoCADProfile Optimization (see

Figure 6).2. A login window appears (see Figure 7). Silverstar is an Autodesk Cloud service. Hence,

you need to enter a valid Autodesk Account login and password. If you dont have an

account yet, please visithttps://accounts.autodesk.comto create an account at no cost.

Once you entered your credentials, the optimization wizard should appear as shown in

Figure 8.
http://labs.blogs.com/Silverstar/Silverstar-Tutorial-1.dwghttp://labs.blogs.com/Silverstar/Silverstar-Tutorial-1.dwghttps://accounts.autodesk.com/https://accounts.autodesk.com/https://accounts.autodesk.com/https://accounts.autodesk.com/http://labs.blogs.com/Silverstar/Silverstar-Tutorial-1.dwg


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Figure 6: Toolbox launcher

Figure 7: Autodesk Cloud login

Figure 8: Optimization Wizard

3. The account e-mail is shown on the top left (see Figure 8). The solution will be sent tothis address.

4. The solution e-mail will contain a PDF report with the PVI configurations and earthworkestimates. Additionally, the user will receive the solution in an ASCII and a LandXML datafile that can be imported into a Civil 3D drawing (see Figure 9). To opt out of theadditional formats, you can simply uncheck them.


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Figure 9: Output format

5. If a design speed is defined for the alignment, the optimization wizard will read this speedinto the Design Speed textbox (see Figure 10). If no design speed is found, you need toprovide a valid speed. The design speed will be taken in the unit of the Civil 3D drawing(mph or km/h). Design speeds will be rounded on the server side to multiples of 5 whenmph, or multiple of 10 when km/h. The server side optimization uses AASHTO 2001design guidelines for the given design speed. Some of the design constraints can beoverridden, as we show in a later step.

Figure 10: Design speed


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6. Select an Existing Ground(EG) surface profile (see Figure 11). For multiple horizontalalignments in the same drawing, select the ground profile for which you wish to receive avertical road profile.

Multiple soil layers can be handled by the optimization algorithm. Make sure that youselect only ground layer surfaces that are for the same horizontal alignment. Selecting

ground surfaces from different alignments may produce wrong results.

In the wizard, you are also able to select ground offsets in order to provide more accuratevolume computations. We will discuss this functionality in Section 0.

Figure 11: Existing ground surface

7. Enter a reusability factor r 1.0 (seeFigure 12). The reusability factor is the percentageof material from the selected ground layer that can be re-used for earthwork filloperations. For example, if we have two different ground layers, overburdenand rock, wecan set the factor for overburden to 1.0, and for rock to 0.5. This means that 100% ofoverburden material from a cut can be re-used in fills. However, only 50% of rock from acut can be used in fills.


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Figure 12: Reusability factor

8. Change the earthwork cost table (see Figure 13). The earthwork costs per surface aregiven in dollars per cubic unit (cubic feet for a design using imperial measures, cubicmeters for metric measures). The cost table can be seen in Figure 13.

Figure 13: Earthwork table

3.2 Borrow/Waste

Similar to a Mass-Haul diagram, we can add borrow and waste pits in the Borrow/Waste window(see Figure 14). In order to add a pit, we use the Add a Borrow/Dump Sitebutton. We then edit


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the Stationto indicate the position where the access road to the pit joins the road on the x-axis ofthe profile.

The Dead Haulis the length of the access road (hence the distance of the pit to the station thatwe added before). Finally, the capacityindicates a borrow or a waste pit. Positive capacity isborrow, negative capacity means waste. For every profile optimization problem, there are already

default borrow and waste pits joining the road at Station 0.0. These pits have infinite capacity butincur considerable costs compared to locally added pits.

Figure 14: Borrow/Waste pits

3.3 Profile Options

The Profile Options window allows us to override the design constraints that are taken fromAASHTO 2001 (see Figure 15). A detailed description of each parameter follows below.


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Figure 15: Profile options

3.3.1 Maximum GradeMaximum grade defines the maximum vertical slope in decimals greater equal to zero. If vdenotes the design speed, the default maximum slope in decimals grows/shrinks linearly with vaccording to Table 1 and Table 2.

Table 1: Maximum slope (metric)

Slope Design Speed

0.05 v> 110

0.07 - 0.05 110 v 50

0.12 - 0.07 50 v

Table 2: Maximum slope (imperial)

Slope Design Speed

0.05 v> 70

0.07 - 0.05 70 v 30

0.12 - 0.07 30 v

3.3.2 Minimum GradeThe minimum required slope in decimals greater or equal to zero. The default value is 0.0. Theminimum grade can be increased for draining purposes. However, the value must be smaller orequal to the Maximum Grade.

Overriding the default value in the case of a single EG centerline (no offsets), will result in anoptimization problem that needs significantly more time to solve than the one using no minimumslope.


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3.3.3 Minimum Tangent LengthThe minimum length required for a tangent between 2 PVIs. If vis the design speed, the defaultvalue for the minimum tangent length in meter is 0.625v, if vis given in km/h, or 3v, if vis givenin mph.

3.3.4 Fix first and last PVI elevation

The user can fix the elevation of the first PVI (i.e. the beginning of the road) and/or the elevationof the last PVI (i.e. the end of the road). The unit is according to the linear unit used in thedrawing (see Figure 16). If, at the same time, the maximum grade is given, the optimizationwizard will check if the fixed PVI elevations can actually be reached with that maximum grade. Ifnot, a tooltip will be show that asks for a feasible configuration (see Figure 16).

Figure 16: Fix initial PVI

3.4 Optimization Options

The Optimization Options window allows for changes of parameters that guide the optimizationprocess (see Figure 17: Optimization Options). A detailed description of each option followsbelow.


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Figure 17: Optimization Options

3.4.1 Number of earthwork sectionsThe number of equally spaced earthwork sections that are going to be used along the horizontalaxis. An earthwork section is a section along the profile that is considered to be assigned to anearthwork crew for excavation and embankment. Hauling is considered as free inside the section(i.e. hauling is done by equipment that is assigned to that section). The length LSof a sectiondepends on the length LA of the alignment and the number nof earthwork sections defined.Hence, LS= LA/n.

Figure 18: Earthwork sections

If a section cannot balance fill and cuts (i.e. there is a demand or a surplus of material), theneeded quantities are hauled in or out from or to other sections. Hauling costs are computedbetween sections and depend on the length of sections.


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3.4.2 Intensity of PVIsFor a given ground surface, the opt imization algorithm creates PVIs automatically. Itapproximates the ground surface with tangents, and the intersection points of these tangents arethe initial PVIs. The PVI Intensity controls the balance of number of lines, vs. close approximationof the ground. Currently, we do not support fixed numbers of PVIs. If there is a need for an exactnumber, we may consider this as a feature for future versions.

Figure 19: PVI Intensity

3.4.3 Solution precisionThe optimal solution is computed with respect to earthwork and hauling costs. The cost value isgiven in dollars and is visible in the PDF report. The solution precision is a dollar value that isrelated to that cost. For example, if the solution precision is set to 0.5 (5), the algorithm

continues to look for a better profile configuration until the cost for a number of adjustments to thebest profile does not change the cost by more than 5. Hence, the smaller this precision, thelonger it takes to solve, but the more precise is the optimal solution.

3.4.4 Maximum solving timeThe maximum allowed solving time is another stopping condition. The algorithm will stop after themaximum solving time, even if it did not find an optimal solution within the given solutionprecision. The algorithm then returns the current best solution. The default value is 60.0 minutes(1 hour). For very large problems (profiles with lengths of 40 km and more), the solving timeshould be increased.

3.4.5 Submission

The final step is to submit the job. This is done by a click on the Finish button (see Figure 20:Submission). On the command console of AutoCAD, the following output should appear:

Exporting Alignments ...Exporting Profiles ...

Command:Command: Sending the Request ...The request was sent successfully


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Figure 20: Submission


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17 |Section 4 Results and Import

4 Results and Import

Currently, the solution for a job together with a report and a logfile are sent to the user by email(see Figure 21).

Figure 21: Solution email

4.1 PDF Report

The PDF Report contains profile and an earthwork information for the optimal solution. Profileinformation can be seen in Figure 22. Blue dots represent PVIs, green dots show the beginningand end of a vertical curve.


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Figure 22: PDF Report (top)

The earthwork plan shows an optimal haul schedule for each soil layer (see Figure 23). An arrowfrom one section to another section indicates a hauling move. The quantity of the correspondingsoil material is given above the arrow. Double-headed arrows inside a section indicate earthworkvolumes that occur inside the section. Green arrows indicate borrow quantities, blue arrowsindicate waste quantities. Quantities are approximations and might not be as accurate as the Civil3D Volume Report.


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Figure 23: Earthwork plan

4.2 ASCII Profile

The ASCII-Solution.txtfile contains the profile in ASCII format. This file can be imported with theProfile creation tools in Civil 3D.

1. Save the file to your local drive.2. In the Civil 3D Home ribbon, select ProfileCreate Profile from File(see Figure 24).3. Select the file that you saved before.4. Confirm the import dialog (see Figure 25).


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Figure 24: Create Profile from File

Figure 25: Create Profile from ASCII

The result of the imported profile can be seen in Figure 26 with PVIs at the beginning and end,and PVIs in between the endpoints indicated by the upwards arrows.


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Figure 26: Imported ASCII Profile

4.3 LandXML Profile

To import the solution into via LandXML, follow the steps below.

1. Save the LandXML solution file to disk.2. Open a new drawing in Civil 3D.3. On the Insert ribbon, in the Import section, click the LandXML button (see Figure 27).

Figure 27: Importing LandXML

4. Select the saved LandXML file.5. In the LandXML import dialog, click on Edit LandXML Settings (see Figure 28).


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Figure 28: Edit LandXML Settings

6. In the LandXML Settings, under Conflict Resolution Settings, change the ConflictResolution to append (see Figure 29).

Figure 29: LandXML conflict resolution

7. Click OK in the LandXML Settings, followed by OK in the Import LandXML dialog.

4.4 Logfile

The logfile is a verbatim output of the optimization algorithm. It contains the information of the joband shows the optimization iterations. Below is a copy of an example logfile:

/usr/local/bin/vertopt /var/spool/vertopt/2vLFUs2kecj1U/input.xml /var/spool/vertopt/2vLFUs2kecj1U/input_solution.txt/var/spool/vertopt/2vLFUs2kecj1U/input_solution.xml /var/spool/vertopt/2vLFUs2kecj1U/input_solution.texProcess file /var/spool/vertopt/2vLFUs2kecj1U/input.xml


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C:\Program Files\Autodesk\AutoCAD Civil 3D 2012\Help\Civil Tutorials\Drawings\Profile-1.dwgLinear unit: meterLength: 483.413ProfSurfs: 1PVI's: 4

0 (0.0000,42.2803) L=0.00001 (126.2319,35.5479) L=113.60872 (305.3804,38.1552) L=160.22923 (483.4128,47.0853) L=0.0000

Design speed: 100

Max slope: 0.0533Min slope: 0.0000Min tangent: 62.5000Road width: 21.9000Side slope: 0.0000Use cross sections: 0Earth sections: 10Earth sub sec: 324Waste pits: 1Borrow pits: 1SLSQ penalty: 14.8490

EG - Surface (1)Start: 0.0000 End: 483.4128Soil type: 0Fill percent: 1.0000Cost tableExcavation cost: 2.3400Load cost: 1.4300Haul cost: 0.0000Embankment cost: 3.3700Waste cost: 0.7500Borrow cost: 2.1000

f(x0) = 65836.3957eval: obj val, sigma, hist dev------------------------------0: 6.583639568e+04, 1.000000000e+01, inf8: 6.461731007e+04, 1.000000000e+01, inf64: 5.748920532e+04, 1.453676911e+01, inf70: 5.608999251e+04, 1.453676911e+01, 2.930685222e+03116: 5.556844006e+04, 9.971384912e+00, 1.798274134e+03...864: 5.533154441e+04, 2.669340003e+00, 3.807882002e+00871: 5.533137229e+04, 2.669340003e+00, 3.313989516e+00930: 5.533048183e+04, 1.529599507e+00, 1.500803563e+00936: 5.533031343e+04, 1.529599507e+00, 1.087946149e+00Function value history tolerance reached.Total iteration: 162Total evaluation: 951Solving time: 4.430000000e+02x:1.043706358e+02 3.262262715e+02 2.008417832e+02 2.428668909e+02

f = 5.533020753e+04, fmax = 5.533168543e+04

Optimal Solution:=================

PVI's:0 (0,39.91) L=01 (104.4,35.19) L=200.82 (326.2,35.05) L=242.93 (483.4,43.43) L=0

Earthwork cost: $55330.21

Earthwork plan:Move 683.59 cu. meter of Soil Type 0 from Section 0 to Section 2Move 183.39 cu. meter of Soil Type 0 from Section 0 to Section 4Move 1412.00 cu. meter of Soil Type 0 from Section 0 to Section 5Move -2174.92 cu. meter of Soil Type 0 from Section 0 to Section 0Move 60.90 cu. meter of Soil Type 0 from Section 1 to Section 2Move -8.61 cu. meter of Soil Type 0 from Section 1 to Section 1Move -707.75 cu. meter of Soil Type 0 from Section 2 to Section 2Move 522.76 cu. meter of Soil Type 0 from Section 3 to Section 4Move -498.89 cu. meter of Soil Type 0 from Section 3 to Section 3Move -673.72 cu. meter of Soil Type 0 from Section 4 to Section 4Move -2388.86 cu. meter of Soil Type 0 from Section 5 to Section 5Move -2629.37 cu. meter of Soil Type 0 from Section 6 to Section 6Move -394.63 cu. meter of Soil Type 0 from Section 7 to Section 7Move 1091.16 cu. meter of Soil Type 0 from Section 8 to Section 5Move 20.72 cu. meter of Soil Type 0 from Section 8 to Section 7Move -1061.10 cu. meter of Soil Type 0 from Section 8 to Section 8Move 2755.18 cu. meter of Soil Type 0 from Section 9 to Section 6Move 410.69 cu. meter of Soil Type 0 from Section 9 to Section 7Move -3021.31 cu. meter of Soil Type 0 from Section 9 to Section 9

Generate PDF...Create solution email for [email protected]


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24 |Section 5 Using Profile Offsets

5 Using Profile Offsets A Case Study

The use of a single EG centerline as shown in Section 3 can be useful for rough estimates andalignments along flat regions. However, for designs with alignments along steep slopes and otherterrain that results in highly irregular cross-sections, Profile Offsetscan be used to increase theaccuracy of earth volume approximations. Solutions using Profile Offsets can be significantlybetter than solutions that use the EG centerline only. However, the increased accuracy usuallyrequires more solving time. This section explains how to use Profile Offsets.

Although comparing the Mass-Haul diagram with the optimized earthwork solution is notrecommended (as explained in Section 6), we still would like to see how an optimized solutioncould affect the Mass-Haul diagram of the previous solution. Hence, we will look at the change ofthe Mass-Haul diagram when switching from the original to an optimized solution.

5.1 Preparing the Drawing

For the following example, we use the file athttp://labs.blogs.com/Silverstar/Silverstar-Tutorial-2.dwg

The file is from the Civil 3D tutorial for Mass-Haul diagrams. For meaningful comparison, wemade the following changes:

1. Using the Create Surface Profiletool from Civil 3D, we added 20 offsets to the EGcenterline, 10 on either side, 10.0 apart (-100.0, -90.0, -80.0, , 0.0, , 80.0, 90.0,100.0). The number of offsets can be chosen by the user. More offsets result in moreaccurate volumes.

2. The optimization engine uses sample line distances of 50.0 (imperial), or 10.0 meter(metric). The sample lines are equally spaced over the whole alignment. We adapted thesample line distance in the drawing for closer match of the Civil 3D volume computationswith the volume approximations of the optimization engine.

3. When using offsets, the optimization engine assumes a Simple Assembly as shown inFigure 30, with two straight lanes and simple daylights with cut slope of 2:1 and fill slopeof 4:1. The lane width depends on the design speed. At low speeds, 36.0 is accountedfor the top of the assembly trapezoid. At high speeds, the total width assumed is108.0.The optimizer does not account for pavement. Hence, we modified the assemblyand the sub-assemblies to use simple lines. (see Figure 30).

Figure 30: Updated cross-section assembly.

4. The profile view of the drawing with offsets looks like Figure 31.
http://labs.blogs.com/Silverstar/Silverstar-Tutorial-2.dwghttp://labs.blogs.com/Silverstar/Silverstar-Tutorial-2.dwghttp://labs.blogs.com/Silverstar/Silverstar-Tutorial-2.dwg


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Figure 31: Silverstar-Tutorial.dwg with offsets.

If we look at the Volume Report for this alignment, we note the following quantities:

Table 3: Initial Volumes.

Volume

Cumulative Cut 13,121Cumulative Fill 10,950

Cumulative Net 2,170

If you decide to do comparisons with your own drawings, please make sure that you modify yourdrawings according to the points described above.

5.2 First Submission with Parameter Changes

Since the original drawing is not constraint-based, we have to override some of the defaultparameters in order to obtain a meaningful comparison.

5.2.1 Design Speed

We derive the design speed from the maximum grade in the original design. If we take the twoend points of the vertical curves at position (849.39, 111.21) and (697.19,100.143), we obtain a

grade of 7.27%. This approximately corresponds to a design speed of 30 mph.

5.2.2 Surface Profile SelectionSelect all of the 21 Surface Profiles in the surface selection of the wizard (see Figure 32).


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Figure 32: Surface selection.

5.2.3 Maximum Grade

We override the default Maximum Slope with 7.27% (see Figure 33).

5.2.4 Start and End-PVI elevationsTo use the same endpoints as the original design, we use the following PVI elevations:

Fix first PVI elevation at: 77.906 Fix last PVI elevation at: 105.000


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Figure 33: Overriding grade and PVI elevations.

5.2.5 PVI IntensityIn our example, we work with relatively slow design speed. This results in shorter minimumtangent length. In order to avoid an excessive amount of PVIs, we therefore reduce the intensity

and move the slider to the center (see Figure 34).

Figure 34: PVI Intensity

5.3 Import and Analysis of Volumes

Import the ASCII-Solution as a new Profile. Open the Prospectorin the Civil 3D Toolspace. UnderCorridors, right-click the Basic Road Corridorand select the Corridor Properties. Change theprofile from Layout Designto File (#) (see Figure 35).


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Figure 35: Change the profile for Mass-Haul.

After clicking OK in the Properties Dialog, your design and Mass-Haul diagram should look similarto the one in Figure 36. The red-white profile is the imported one.

Figure 36: Optimized solution for Mass Haul-2.dwg.

From the new Mass-Haul diagram, we can see that the optimizer created a solution that is nearly

balanced. The comparison of the volumes in the Civil 3D Volume Report with the volumes givenin the Profile Optimization Report are shown in Table 4.

Table 4: Volume differences between Civil 3D and Optimizer.

Civil 3D Volume Optimizer Volume

Cumulative Cut 9,953 9,562

Cumulative Fill 9,537 9,562

Cumulative Net 415 0


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There is a difference of 415 yd3, mostly in the cut volumes. One reason for the volume

discrepancy is the use of earthwork sections. The beginning or the end of an earthwork sectioncan fall between sample lines. In such a case, the optimizer places an additional sample line atthe endpoint of the earthwork section, which results in more sample lines on the server side.

5.4 Change of Excavation Cost

Using the default parameters, the optimizer will always try to produce a balanced solution. This isbased on the optimizers assumptionthat default borrow and waste pits are located 500.0 (or500.0 meters) from Station 0+0.0. Hence the hauling of excessive waste to that pit location ismore expensive than using cut material along the road. If we want to use more cut material fromoutside, we can influence the optimization by increasing the excavation cost.

In our study, we submit the problem again with identical parameters as in Section 5.2, except forthe hauling costs. In our new submission, we set them to $5.80/ yd

3(see Figure 37).

Figure 37: New excavation costs.

The import of the new solution results in the Mass-Haul diagram in Figure 38. The volumes aregiven in Table 5.

Table 5: Volumes with high excavation costs.

Civil 3D Volume Optimizer Volume

Cumulative Cut 8,445 8,189

Cumulative Fill 9,732 9,840

Cumulative Net -1,287 -1,651


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Figure 38: Mass-Haul after solution with higher cut costs.


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6 Limitations

6.1 Cross-Sections

If a single EG centerline only is used, the current version of the profile optimization algorithm usesrectangles to approximate cross-sections. In other words, the optimization algorithm assumesthat there exist retaining wallsalong the alignment. Hence, the user has to be aware of thefollowing implications:

1. If a single EG centerline is used, the result is an optimal centerline with respect toearthwork and hauling, only if cross-section assemblies with retaining walls on each sideare used.

2. After importing a profile from the profile optimization algorithm, switching the profile of anexisting corridor to the new profile may result in errors if custom cross-section assemblieswithout retaining walls are used in the existing corridor.

If Profile Offsets are used, the algorithm uses a Simple Assembly as described in Section 5.1.

The optimizer looks for the intersection of the daylight side slope with the ground surface. If nointersection is found that is at most 6 times the road width away from the centerline, a retainingwall is placed and the same limitations apply as to the single EG centerline.

6.2 Mass-Haul and Volume Reports

There are important considerations, when using Mass-Haul diagrams and Volume Reports on aprofile from the profile optimization algorithm.

1. Volumes given by the Civil 3D Volume Report may differ from the volumes given from theProfile Optimization Report. The optimizer uses cross-section area approximations thatare based on the Profile Offsets. The more offsets, the closer the volumes will be. Also,the sample distances used in the optimizer are either 50.0 or 10 meter apart. Hence,

sample lines with the same distances should be used for Civil 3D Volume Reports.Furthermore, As mentioned in Section 6.1, when using a solution with EG centerline only,the algorithm assumes retaining walls on either side of the road. You will need to adaptyour assemblies accordingly.

2. You should not use a Mass-Haul diagram to quantify a solution from the optimizationalgorithm with a manual solution. The optimization algorithm uses fixed earthworksections and assumes free hauling within these sections. A Mass-Haul diagram placesfree-haul sections dynamically (having the center of the section at a balance point of thediagram). Furthermore, the optimization algorithm uses hauling costs that depend on thehauling distance. The Mass-Haul diagram considers volumes only. Hence, the twomethods are not really suitable for comparisons.

Vertical Profile Optimization for the Clous Civil3d

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